The present disclosure relates to additive manufacturing systems for printing or otherwise building three-dimensional (3D) parts with layer-based, additive manufacturing techniques. In particular, the present disclosure relates to purge stations for use with print heads in additive manufacturing systems.
Additive manufacturing systems are used to print or otherwise build 3D parts from digital representations of the 3D parts (e.g., STL format files) using one or more additive manufacturing techniques. Examples of commercially available additive manufacturing techniques include extrusion-based techniques, jetting, selective laser sintering, powder/binder jetting, electron-beam melting, and stereolithographic processes. For each of these techniques, the digital representation of the 3D part is initially sliced into multiple horizontal layers. For each sliced layer, a tool path is then generated, which provides instructions for the particular additive manufacturing system to print the given layer.
For example, in an extrusion-based additive manufacturing system, a 3D part may be printed from a digital representation of the 3D part in a layer-by-layer manner by extruding a flowable part material. The part material is extruded through an extrusion tip or nozzle carried by a print head of the system, and is deposited as a sequence of roads on a substrate in an x-y plane. The extruded part material fuses to previously deposited part material, and solidifies upon a drop in temperature. The position of the print head relative to the substrate is then incremented along a z-axis (perpendicular to the x-y plane), and the process is then repeated to form a 3D part resembling the digital representation.
In fabricating 3D parts by depositing layers of a part material, supporting layers or structures are typically built underneath overhanging portions or in cavities of 3D parts under construction, which are not supported by the part material itself. A support structure may be built utilizing the same deposition techniques by which the part material is deposited. The host computer generates additional geometry acting as a support structure for the overhanging or free-space segments of the 3D part being formed. Support material is then deposited from a second nozzle pursuant to the generated geometry during the printing process. The support material adheres to the part material during fabrication, and is removable from the completed 3D part when the printing process is complete.
During a build process, residual amounts of build and support materials may seep out of the corresponding extrusion tips after the extrusion processes are halted. These residual materials may interfere with subsequent extrusions, and may also potentially clog the extrusion tips. As such, it is desirable to periodically clean the extrusion head with a cleaning assembly to prevent material buildup in the extrusion tips. Current cleaning assemblies typically require precise calibrations during installation to ensure adequate alignment with the extrusion tips of the extrusion head.
Such calibrations are time consuming and require skillful technicians. Thus, when portions of a cleaning assembly are damaged and need replacement, the cleaning assembly typically requires recalibration before being operated. This delays the operation of the additive manufacturing system and may increase service costs. Thus, there is a need for a cleaning assembly that is efficient for cleaning extrusion heads, and is easy to repair with reduced recalibration requirements.